1. Field of the Invention
The present invention relates generally to the field of catheters for venous or arterial cannulation, which are inserted into a blood vessel with a hollow needle having a needle hub. More specifically, it relates to an occludable catheter apparatus for blocking the flow of blood from the catheter after withdrawal of the insertion needle. The apparatus includes a catheter hub having a side wall with a stiff but compressible tubular side wall portion, a proximal end, a distal end, and a catheter extending axially outward from the distal end. Two spaced apart locking members protrude tangentially outward from the hub tubular side wall portion, and each contains a stiff structural member extending into the side wall portion. The locking members are pressed toward each other to collapse the hub side wall portion. The catheter hub contains compressible, resilient sealing material such as a foam rubber for sealingly compressing during hub collapse, the sealing material having an axial opening. To use the apparatus, the needle and needle hub are inserted into the apparatus through the catheter hub. The insertion needle and catheter penetrate a blood vessel, and then the needle is withdrawn from the catheter and catheter hub. After the needle is withdrawn, the locking members are gripped by the medical provider and the sealing material is thereby compressed to prevent blood from escaping from the catheter. The sealing material closes the hub completely after the tip of the needle passes out of the hub to prevent blood from escaping until the infusion set is connected to the catheter hub proximal end. The locking members may optionally include latching means for holding the locking members pressed together and the catheter hub collapsed.
2. Description of the Prior Art
There have recently been several catheter devices containing means for minimizing the escape of blood after the catheter insertion needle is removed from the device. The introduction of these devices is largely the result of recognition of the dangers presented by contact with AID's, hepatitis and other blood borne diseases and infections by the medical provider. Proper disposal of the contaminated needle has also been an issue.
Lemieux, U.S. Pat. No. 5,127,905, issued on Jul. 7, 1992, discloses a stickless catheter with a manual shut-off valve. Lemieux includes a catheter assembly where the catheter hub contains a pivotable, manually operable mechanism capable of pinching the catheter tube to close the fluid path,. A finger-like insert is passed through a slot in the catheter hub assembly and into direct manual contact with the catheter and is pivoted against the catheter to pinch close the catheter. A problem with Lemieux is that the pinched catheter tube creates an imperfect seal, and if even a drop of contaminated blood escapes, a substantial danger is created to the medical provider. The closing mechanism is also awkward to hold in the occluding position.
Beck, et al., U.S. Pat. No. 5,215,527 issued on Jun. 1, 1993, teaches a catheter introducer assembly which combines a catheter and an introducer which cooperate to provide infusion of drugs. This is supposedly accomplished with no return blood flow. The introducer is a short thin-walled device which receives the catheter. The catheter has several very fine openings which have a dimension to prevent blood backflow, but which allow the infusion of medication for therapy because of pressure imparted in the fusion flow of the drugs. A problem with Beck is that the use of very fine holes would not permit ready flow of fluid into or out of a blood vessel. The fine hole construction would also be costly to manufacture.
Holdaway, et al., U.S. Pat. No. 5,030,205, issued on Jul. 9, 1991, and Holdaway et al., U.S. Pat. No. 5,156,792, issued on Oct. 20, 1992, reveal a catheter assembly for prevention of blood leakage. Holdaway includes a catheter which forms the distal end of the catheter hub and restricts the inner diameter of the catheter cannula to a wiping fit with the engaged insertion needle. A problem with Holdaway is that the contacted catheter cannula apparently does not fully block the flow of blood after the needle is removed and before the infusion set is attached. Another problem is that the contracted catheter cannula continues to restrict the flow of fluids after attachment of an infusion set.
Van Heugten, U.S. Pat. No. 5,053,014, issued on Oct. 1, 1991, teaches a catheter with a controlled valve for preventing blood backflow. Van Heugten includes a catheter hub containing a membrane for preventing backflow. A membrane opener operates upon the insertion of a luer locking mechanism into the catheter hub. When the needle is withdrawn from the membrane opener and membrane, the membrane automatically seals the passageway of the catheter hub. When a tubing set is connected to the catheter hub, the tubing set connector actuates the valve membrane opener to open the valve membrane so that fluids may be delivered through the catheter to a patient. A problem with Van Heugten is that it is complex, having a number of moving parts, expensive to manufacture, and relatively unreliable. The membrane might leak at the wrong moment.
Chang, U.S. Pat. No. 5,092,845, issued on Mar. 3, 1992, discloses a catheter with a needle gasket for preventing blood backflow. Chang reveals a catheter assembly with a needle guard that slides along the needle to shield the distal tip of the needle after the needle is withdrawn from the patient. A gasket is formed with the needle in place by filling an aperture around the needle with an adhesive, which cures to create a formed-in-place gasket. A problem with Chang is that the formed-in-place gasket apparently would not completely seal against backflow once the needle is fully removed from the catheter. Yet the gasket would restrict free fluid flow after attachment of an infusion set.
Bornaldo, U.S. Pat. No. 5,154,703, issued on Oct. 13, 1992, teaches a bloodless catheter apparatus. Bornaldo includes a housing having a longitudinal passageway extending therewithin between an upstream end and a downstream end which has a catheter tube extending outwardly from its downstream end in fluid communication with the longitudinal passageway. A hollow needle is mounted in the passageway. A valve assembly is provided which includes a valve element made of material which is self-sealing after puncture by the needle point, disposed transversely in the longitudinal passage between the needle point and housing upstream end. A problem with Bornaldo is that the valve assembly would be complex and expensive to produce.
It is thus an object of the present invention to provide a catheter apparatus which prevents the escape of blood during the time between removal of the insertion needle and connection of an infusion set.
It is another object of the present invention to provide such an apparatus which is highly efficient and reliable.
It is still another object of the present invention to provide such an apparatus which is easy to use.
It is finally an object of the present invention to provide such an apparatus which is relatively inexpensive to manufacture.